Vibrating roller

ABSTRACT

Vibrating roller provided with a shaft, wherein, in each of the possible directions of rotation of the roller shaft, the centrifugal force can be adjusted at will by automatically adjusting or modifying the eccentric mass, such mass comprising at least one part idle relative to the shaft, and at least one part rigid with the shaft, which are arranged relative to one another in such a way that upon reversing the direction of rotation of the shaft, their respective centres of gravity take distinct positions, the centrifugal forces generated thus attaining predetermined levels in each case. The roller also has a damping means.

United States Patent [1 1 Lebrero Martinez [54] VIBRATING ROLLER [76I Inventor: lsidoro Lebrero Martinez, Avda.

Fco. Caballero, 23, Zaragoza, Spain [22] Filed: May 3, 1974 [2]] Appl. No: 466,901

[111 3,892,496 [4 1 July 1, 1975 Primary Examiner-Mervin Stein Assistant Examiner-Steven Hawkins Attorney, Agent, or FirmWenderoth, Lind & Ponack 5 7 ABSTRACT Vibrating roller provided with a shaft, wherein, in each of the possible directions of rotation of the roller shaft, the centrifugal force can be adjusted at will by automatically adjusting or modifying the eccentric mass, such mass comprising at least one part idle relative to the shaft, and at least one part rigid with the shaft, which are arranged relative to one another in such a way that upon reversing the direction of rotation of the shaft, their respective centres of gravity take distinct positions, the centrifugal forces generated thus attaining predetermined levels in each case. The roller also has a damping means.

6 Claims, 7 Drawing Figures 1 VIBRATING ROLLER BACKGROUND OF THE INVENTION The invention relates to vibrating rollers for machines designed to roll or tamp various types of ground surfaces, for example, blankets of asphaltic agglomerates and pebble gravel-cement compounds, and in particular to a roller by means ofwhich the use of two different kinds of such rollers depending upon the material to be tamped in each given case, since their intrinsic physical conditions and characteristics are not the same, is avoided,

As a matter of practice. uniform or very near to the natural frequencies of the ground vibrations are necessary which are arranged to vary depending upon the composition and conditions of the ground to be tamped from 23 to Hz. These vibrations in combination with the mechanical impact of the roller, are produced by the centrifugal force transmitted thereto by its actuation or driving axis and ensure maximum performance of the machine in each moment.

Frequencies up to Hz of roller vibrations are necessary, if asphaltic agglomerates comprising pebble gravel-cement compounds are to be tamped, this involving mechanical impacts much lower (approximately half) than those necessary for tamping grounds, apart from much higher translational speeds of the machine.

This enormous difference in work to be carried out in the two circumstances mentioned above, has made it necessary up to now to employ a distinct machine in each case in order to attain maximum efficiency. This is because in the machines used at present an increase in the frequency of the driving or actuating shaft results in a much higher increase of the centrifugal force (which is a quadratic function of the frequency) and thus of the mechanical impacts of the vibrating roller. The opposite situation occurs in tamping asphaltic agglomerates and pebble gravel-cement soils, i.e. a higher frequency with remarkable decrease of mechanical impacts.

SUMMARY OF THE INVENTION According to the invention there is provided a vibrating roller provided with a shaft wherein, in each of the possible directions of rotation of the roller shaft the centrifugal force can be adjusted at will by automatically adjusting or modifying the eccentric mass, such mass comprising at least one part idle relative to the shaft, and at least one part rigid with the shaft, which are arranged relative to one another in such a way that upon reversing the direction of rotation of the shaft their respective centres of gravity take distinct positions, the centrifugal forces generated thus attaining predetermined levels in each case. The roller also includes damping means.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will be further described with reference to the accompanying drawings, which illustrate various embodiments of the invention, which are given by way of example only.

In the drawings:

FIG. I is a cross-section of a roller assembly.

FIG. 2 is a longitudinal section of the assembly of FIG. 1.

FIG. 3 is a view similar to FIG. 1 with the assembly in another position.

FIG. 4 is a perspective view showing the displacement of the bodies of FIGS. I, 2 and 3.

FIG. 5 is a diagrammatic front view of a second embodiment.

FIG. 6 is a longitudinal section of the embodiment of FIG. 5.

FIG. 7 shows the arrangement of the bodies in this second embodiment when the direction of rotation is opposite to that considered in FIG. 5.

DETAILED DESCRIPTION OF THE INVENTION Referring to FIGS. 1 and 2, outer massive bodies 2 and additional massive bodies 3 (FIG. 2) are mounted on the actuating or driving shaft 1 (FIG. 1). Bodies 2 define inside thereof a housing for bodies 3 and a container to receive a liquid 4 for damping mechanical shock occurring upon reversing the direction of rotation of the shaft.

The outer body 2 is formed with a projection 5 (FIG. 4). The region of contact between this projection and the projection 7 of the additional body 3 is indicated by line 6 (FIG. I), the direction of rotation in this case being counterclockwise.

Openings 8 are formed in the additional body 3 and in the outer body 2 through which the damping liquid will flow upon reversing the direction of rotation. The region of contact between the bodies when the direction of rotation of the driving shaft is clockwise, is indicated by line 9 (FIG. 3).

The assembly of the bodies 2 is eccentric relative to the shaft 1, bodies 2 being rigidly fixed thereto by any conventional means such as keys 10 (FIG. 2). The inner mass 3 also rotates eccentricly in a idle manner about shaft 1 and takes predetermined positions depending upon the direction of rotation of bodies 2, when its projection 7 abuts against the projection 5 of the outer bodies 2. Thus by rotating the mass 3 through relative to the mass 2, which rotation occurs automatically when the direction of rotation is reversed, the eccentric mass is modified since in the case shown in FIG. 1 the masses of both bodies 2 and 3 have the same effect, while in the case shown in FIG. 3 they have a contrary effect relative to one another. This may be alternatively expressed by saying that the distance of the centre of mass of the system from the axis of rotation is different from the two positions of body 3. In the first case the necessary predetermined force is attained by addition of masses, while in the second case by difference of masses. The rotation of the driving shaft 1 is caused by any known kind of motor or engine, the frequency thereof being adjustable at will.

In order to eliminate sudden shocks caused by this movement of the bodies from one position to another, there is provided, as mentioned above an adjustable damping means to damp the shock energy.

The above description made with reference to FIGS. I to 4 relates to hydraulic damping in which the liquid container 4 is provided inside the outer body 2, such a container being filled through a plug suitably arranged.

With such an arrangement upon reversing the direction of rotation of the driving shaft, the inner massive body 3 which is idle with respect to the shaft, due to inertia tends to continue to rotate in the same direction until its projection 7 abuts projection 5. This can occur only when the liquid 4 has displaced to the place previously occupied by the body 3. This displacement of the liquid 4 can occur as quickiy or as slowly as desired de pending upon the size or the surface of the gaps 8 between the bodies 2 and 3, whereby the speed with which the projections 5 and 7 approach each other will be predetermined in each case and the shocks can be damped to the desired extent.

In the second embodiment (FIGS. 5 and 7) having mechanical dampening of shocks, outer masses 1] and inner masses I2 are shown in FIG. 5 at a position determined for rotation in the clockwise direction. Projection 13 which is rigid with mass 11 is housed in a recess formed in the mass 12. FIG. 7 shows the position taken by the mass while rotating in the opposite direction.

The mechanical damping in this case is illustrated in FIG. 6. Friction is produced by the shoes 14, which can be metallic or not, and are positioned between the outer masses 11 (one or more) and the inner mass 12. The shoes 14 are urged by springs 15 to provide the frictional force necessary for the driving engagement, by making the same rigid with one another up to a determined frequency, with a subsequent sliding therebetween when the centrifugal force generated in the idly rotating mass I2 on the driving shaft 1 is higher than the frictional force, thus avoiding violent shocks. Adjusting screws I6 have the function of ensuring that the force of the springs 15 on the shoes 14 produce the necessary friction in each case.

I claim:

I. In a vibrating roller device provided with a rotatable shaft having an eccentric mass mounted therearound, and wherein, in each of the possible directions of said shaft, the centrifugal force can be selectively adjusted by automatically adjusting said eccentric mass; said device further including a damping means; the improvement wherein:

said eccentric mass comprises:

a pair of outer masses defining therebetween a chamber;

an inner mass positioned in a portion of said chamber;

the remainder of said chamber defining a liquid receiving container;

one of said inner mass or said pair of outer masses being rigidly fixed to said shaft, and the other being idly mounted on said shaft; and

said inner mass and said pair of outer masses being relatively arranged such that, upon a reversal of direction of rotation of said shaft. the respective centers of gravity thereof take distinct positions, and the centrifugal forces thus generated attain respective predetermined levels; and

said damping means comprises liquid filling said liquid receiving container.

2. The improvement claimed in claim 1, further comprising openings of variable cross section, between said outer masses and said inner mass and said liquid receiving container, through which said liquid flows upon changing of position of said masses upon reversal of direction of rotation of said shaft.

3. The improvement claimed in claim 1, wherein said outer masses are rigidly fixed to said shaft, at least one of said outer masses having a lateral disc with a semicircular projection, said inner mass having at least one projection over substantially a quadrant thereof, said projection of said at least one outer mass abutting said projection of said inner mass.

4. In a vibrating roller device provided with a rotatable shaft having an eccentric mass mounted therearound, and wherein in each of the possible directions of said shaft, the centrifugal force can be selectively adjusted by automatically adjusting said eccentric mass; said device further including a damping means; the improvement wherein:

said eccentric mass comprises:

a pair of outer masses;

an inner mass positioned between said outer masses;

one of said inner mass or said pair of outer masses being rigidly fixed to said shaft, and the other being idly mounted on said shaft; and

said inner mass and said pair of outer masses being relatively arranged such that, upon a reversal of direction of rotation of said shaft, the respective centers of gravity thereof take distinct positions, and the centrifugal forces thus generated attain respective predetermined levels; and

said damping means comprises a pair of shoes, one

each positioned between said inner mass and one of said outer masses; and adjustable spring means for urging said shoes toward said mass mounted idly on said shaft to produce a frictional force to compensate said centrifugal forces up to said predetermined levels.

5. The improvement claimed in claim 4, wherein said outer masses are rigidly fixed to said shaft; and said spring means comprise springs mounted in said outer masses and bearing against said shoes, and adjusting screw means extending through said outer masses for adjusting the tension of said springs.

6. The improvement calimed in claim 5, wherein said outer masses are substantially circular in shape, and said inner mass is semicircular in shape with substantially radial edges; and further comprising a projection extending from at least one of said outer masses abutting one of said edges of said inner mass. 

1. In a vibrating roller device provided with a rotatable shaft having an eccentric mass mounted therearound, and wherein, in each of the possible directions of said shaft, the centrifugal force can be selectively adjusted by automatically adjusting said eccentric mass; said device further including a damping means; the improvement wherein: said eccentric mass comprises: a pair of outer masses defining therebetween a chamber; an inner mass positioned in a portion of said chamber; the remainder of said chamber defining a liquid receiving container; one of said inner mass or said pair of outer masses being rigidly fixed to said shaft, and the other being idly mounted on said shaft; and said inner mass and said pair of outer masses being relatively arranged such that, upon a reversal of direction of rotation of said shaft, the respective centers of gravity thereof take distinct positions, and the centrifugal forces thus generated attain respective predetermined levels; and said damping means comprises liquid filling said liquid receiving container.
 2. The improvement claimed in claim 1, further comprising openings of variable cross section, between said outer masses and said inner mass and said liquid receiving container, through which said liquid flows upon changing of position of said masses upon reversal of direction of rotation of said shaft.
 3. The improvement claimed in claim 1, wherein said outer masses are rigidly fixed to said shaft, at least one of said outer masses having a lateral disc with a semicircular projection, said inner mass having at least one projection over substantially a quadrant thereof, said projection of said at least one outer mass abutting said projection of said inner mass.
 4. In a vibrating roller device provided with a rotatable shaft having an eccentric mass mounted therearound, and wherein in each of the possible directions of said shaft, the centrifugal force can be selectively adjusted by automatically adjusting said eccentric mass; said device further including a damping means; the improvement wherein: said eccentric mass comprises: a pair of outer masses; an inner mass positioned between said outer masses; one of said inner mass or said pair of outer masses being rigidly fixed to said shaft, and the other being idly mounted on said shaft; and said inner mass and said pair of outer masses being relatively arranged such that, upon a reversal of direction of rotation of said shaft, the respective centers of gravity thereof take distinct positions, and the centrifugal forces thus generated attain respective predetermined levels; and said damping means comprises a pair of shoes, one each positioned between said inner mass and one of said outer masses; and adjustable spring means for urging said shoes toward said mass mounted idly on said shaft to produce a frictional force to compensate said centrifugal forces up to said predetermined levels.
 5. The improvement claimed in claim 4, wherein said outer masses are rigidly fixed to said shaft; and said spring means cOmprise springs mounted in said outer masses and bearing against said shoes, and adjusting screw means extending through said outer masses for adjusting the tension of said springs.
 6. The improvement calimed in claim 5, wherein said outer masses are substantially circular in shape, and said inner mass is semicircular in shape with substantially radial edges; and further comprising a projection extending from at least one of said outer masses abutting one of said edges of said inner mass. 